1. Field of the Invention
The present invention relates to a compartment ventilating apparatus which is installed in side walls of refrigerators, freezing chambers, cold storages and the like to discharge indoor air when a door is closed and to take in outdoor air when the door is opened, so as to facilitate the opening/closing operation of the door, whereby a rapid increase of an indoor air pressure is prevented while the thus taken in outdoor air facilitates the door's opening operation.
2. Description of the Prior Art
In a conventional compartment ventilating apparatus, a ventilation unit is installed in a through-hole or opening portion of a side wall of a compartment. The ventilation unit comprises: a casing mounted in the opening portion of the side wall in an insertion manner; a partition element mounted in the casing in an insertion manner to partition the interior of the casing into an inner air space and an outer air space; a first closing plate disposed outside the partition element so as to open and close a first ventilation hole; a second closing plate disposed inside the partition element so as to open and close a second ventilation hole; a guide shaft slidably mounted in each of an axial hole of a central portion of the partition element, an axial hole of a central portion of the first closing plate and an axial hole of a central portion of the second closing plate; a stopper portion formed in one of opposite ends of the guide shaft so as to abut against the first closing plate or the second closing plate; a seat plate having its axial hole slidably receive a threaded rod portion of the other of the opposite ends of the guide shaft; a nut threadably engaged with the threaded rod portion of the guide shaft to support the seat plate; and, a compression spring interposed between the first closing plate or the second closing plate and the seat plate to have the first closing plate and the second closing plate abut against an inner surface and an outer surface of the partition element. The opening portion of the side wall of the compartment has its opposite ends covered with louvers and insect nets. The louvers comprise an indoor louver and an outdoor louver.
However, in the conventional compartment ventilating apparatus having the above construction, since only one ventilation unit is employed in the compartment to separate the indoor air from the outdoor air therein, the indoor louver is often subjected to the formation of dew when a difference in temperature between the indoor air and the outdoor air is large. The thus formed dew or frost, is built up in the ventilation area of the convention unit in the form of ice to decrease the ventilation area in cross section, which impairs the conventional unit in pressure-regulating properties.
Further, in the conventional compartment ventilating apparatus, since the only one guide shaft slidably passes through the partition element and the circular axial holes of the central portions of the first and the second closing plate, the first and the second closing plate often vibrates in operation to frequently catch an inner surface of the casing, which causes a malfunction of the conventional unit.